io BYZANTINE CHURCHES CHAP.
not always equa!5 and may be covered with barrel vaults (p. 214) or with cross-groined vaults (p. 198), The berna is usually a bay added to the eastern arm. The angle chambers have either cross-groined vaults or flat dome vaults* In general the churches of this type in Constantinople do not differ from the numerous churches of the same class in the provinces.1
A lobed cruciform plan is found in only one church in Constantinople, that of S. Mary of the Mongols (p. 277). Here the central dome is supported on four piers set across the angles of the square> so that the pendentives do not come to a point as usua!5 but spring from the face of the piers. Against each side of the square a semidome is set, thus producing a quatrefoil plan at the vaulting level.
Both trefoiled and quatrefoiled churches are not uncommon in Armenia, such as the cathedral at Etschmiadzin;2 trefoiled churches of a later date are found in the western province$5 and examples have been published from Servia/ Salonica,4 and Greece.5
An unusual form of the cross plan is seen in the building known as Sanjakdar Mesjedi (p. 267)5 where a cross is placed within an octagon. Probably the building was not originally a church. It resembles the octagon near the Pantokrator (p. 270)5 and may, like it, have been a library.
Single Hall Churches.—The plans hitherto considered have all been characterised by the presence of aisles, galleries, or other spaces adjoining the central area. The churches of the present class consist simply of an oblong hall, terminating in an apse, and either roofed in wood, or covered with domes placed longitudinally, and resting to north and south on wall arches. Examples of this plan are found in Monastir Mesjedi (p. 264), S. Thekla (p. 211), Bogdan Serai (p. 284), and in the memorial chapels attached to the Pantokrator (p. 235), and the Chora (p. 309), In
1 For local variations in late churches in Greece, see Traquair's * Churches of Western Mani," Annual of British School at Athens, xv. 1908.
2 Strzygowski, *Bas Etschmiadzin Evangeliar/ Byxant. Denkm&ler, i., 1891,
3 Ravanica, F. Kamtz, Serbians by&anthche Monument*, Wien, 1862,
4 Pullan and Texier, S. Ettas.
6 G. Lampakis, Let Antiquitfs chrttiennes de la Gr%cey Athens, 1902*